The present invention relates to a refrigerant suction and discharge apparatus of a hermetic compressor for high efficiency and noise reduction according to the application of a new refrigerant.
A conventional hermetic compressor includes a casing 1 comprising a lower half-shell 2 and an upper half-shell 3, wherein the two shells are hermetically joined as shown in FIG. 1, and a compression mechanism 4 having a crankshaft 6 and an electric motor mechanism 5 rotating the crankshaft 6 are positioned at the upper and lower parts respectively of a frame 7 disposed in the internal central portion of the casing 1.
The compression mechanism 4 includes a cylinder 9, a piston 10 reciprocating within the cylinder 9, and a slider 11 reciprocating the piston 10 according rotation of the crankshaft 6, and the electric motor mechanism 5 includes a rotor 12 and a stator 13 for rotating the crankshaft 6 by means of induced magnetism. To the lower portion of the crankshaft 6 is attached a propeller 17 drawing oil 15 in the bottom of the lower half-shell 2 through a central hole 16 of the crankshaft 6.
The rotation of the crankshaft 6 reciprocates the piston 10 within the cylinder 9 resulting in repeated suction, compression, and discharge of refrigerant gas. During this operation, noise is emitted so that means for reducing noise is mounted at a cylinder head.
FIG. 2 shows a conventional refrigerant suction and discharge passageway and means for reducing noise, which are disposed at the cylinder head, according to the movement direction of refrigerant gas.
The conventional refrigerant suction and discharge apparatus and means for reducing noise comprise a suction muffler 20 having a suction inlet opening 22, a suction chamber 24 as a space drawing refrigerant gas, a compression chamber 25 compressing the refrigerant gas drawn from the suction chamber 24 by compression force of the piston 10, a discharge chamber 26 as a space releasing the refrigerant gas in the compression chamber 25, a head cover 29 enclosing the outer space of the cylinder head and guiding the refrigerant gas, a discharge muffler 21 reducing noise of discharge gas, and a discharge pipe 31 guiding the discharge gas delivered from the discharge muffler 21.
In the conventional hermetic compressor, the rotor 12 and the crankshaft 6 is rotated by electric power, and the piston 10 reciprocates within the cylinder 9 by means of a scotch yoke mechanism according to the rotation of the crankshaft 6, resulting in repeated suction, compression, and discharge of refrigerant gas.
That is, after the refrigerant gas drawn into the casing 1 through a suction pipe 30 fills up the interior of the casing 1, it is drawn through the suction muffler 20 into the cylinder 9 in which it is compressed by the piston 10, and is discharged through the discharge muffler 21.
However, in the aforementioned conventional hermetic compressor, the refrigerant gas fills up the interior of the casing 1 prior to suction, the suction inlet opening 22 of the suction muffler 20 positioned at the upper half-shell 3 is considerably apart from the suction pipe 30 positioned at the lower half-shell 2, and a suction line 23 of the suction muffler 20 is curved and elongated, and thus the distance from suction to discharge is long.
As a result, the refrigerant gas movement is delayed and the gas is overheated, the ratio volume of the gas is increased and the density is decreased, resulting in lowered heat efficiency. Additionally, since the suction inlet opening 22 of the suction muffler 20 cannot guide suction gas from the suction pipe 30 properly, the quantity of the suction gas is small.
Furthermore, because the compression ratio, which has an effect on noise, is about 2.5 times as large R-134a as for R-12 and the noise value increases on account of changing conventional refrigerant (R-12) into new refrigerant (R-134 a). As a result noise reduction by means of the suction muffler 20 and the discharge muffler 21 is no longer satisfactory.
That is, noise is reduced by lowering refrigerant density through mufflers, but noise reduction for new refrigerant (R-134a) is restricted because of the high compression ratio for R-134a refrigerant as compared with R-12.